To participate in an activity that results in ejaculation. Usually exclaimed, directed at a person. Said person is most likely in a situation that the commentator believes will end in orgasm. "Nut" refers to semen, and thus, to get your nut, is to ejaculate.

When the female counterpart is aware of the meaning of this phrase, it is usually more polite to instead say, "GYN". The female may or may not understand this abbreviation.